A hypocycloidal cranking apparatus converts rotational motion into rectilinear motion. This apparatus can also operate in the reverse, transforming rectilinear motion into rotational motion to drive devices such as reciprocating piston engines.
In a typical hypocycloidal cranking apparatus, rotational motion is delivered to the device through an input shaft attached to a power source. A crank arm is affixed to the input shaft such that the crank arm rotates in unison with each rotation of the input shaft. A sprocket shaft is offset from the input shaft and is fixedly mounted within the crank arm. An external toothed orbiting member is rotatably mounted on the sprocket shaft, and the teeth of the orbiting member mesh with the teeth within an internal toothed stator member. An eccentric arm is fixedly mounted on the orbiting gear face such that the eccentric arm rotates in unison with each rotation of the crank arm, but in the opposite rotational direction. An output shaft or rod journal is offset from the eccentric arm.
As the input shaft rotates, the crank arm rotates and the sprocket shaft mounted orbiting member rotates within the internal toothed stator member, causing the loci of axis points on the output shaft to transcribe a straight line between the extreme positions of the output shaft. This rectilinear motion can be used to power a variety of devices, including but not limited to, air compressors.
In a typical hypocycloidal cranking apparatus the stator member is machined from a single piece of metal. (See e.g. Wiseman U.S. Pat. No. 6,510,831). Because a tight mesh is required between the teeth of the orbiting member and stator member, the teeth on these components are fabricated with high precision. Manufacture of this type of machined gear is costly, difficult, and time consuming. Improper engagement between the metal teeth of the orbiting member and the teeth of the stator member will result in high wear, vibration, noise and eventually fatigue failure of the gear teeth in one or both components. In addition, the metal on metal contact requires lubrication to reduce wear and damage to these components. In the event that the orbiting member or stator member is damaged, it must be replaced with a completely new component.
A recent published patent application (U.S. patent application Ser. No. 11/131,819) suggested the use of a chain or belt as a replacement for the conventional machined stator member. In this device, the chain or belt was sandwiched between a front and back ring and was not rigidly fixed on its outer circumference. The application suggested that the flexible chain or belt would prevent or reduce clogging of foreign material within the unit. While this is an appealing idea, a flexible stator member will not work in practice. The stator member must remain rigid in order to synchronize the motion of the orbiting member rotating within it. A hypocycloidal cranking apparatus operating within a flexible stator member would induce destructive oscillations in the device, potentially damaging the crank assembly.
The present invention provides an improved hypocycloidal cranking apparatus that avoids the disadvantages of the prior art by providing a stator member that is practical, inexpensive and easy to implement and maintain.